新汶凹陷官庄组沉积演化特征

摘要

With the aid of sequence stratigraphic and sedimentological principles,the types,vertical evolution and planar distribution of sedimentary facies are dealt with on the basis of field observations of sedimentary structures,thin section examination and grain size analysis for the Guanzhuang Formation in the Xinwen depression,Shandong.The three types of sedimentary facies are recognized including the alluvial fan,braided stream and lake facies,and two sedimentary systems are developed including alluvial fan-braided stream-lake and alluvial fan depositional systems in an ascending order in the Guanzhuang Formation.The sedimentary evolution covered the alluvial fan and braided stream deposits during the early stage,lake deposits during the middle stage and alluvial fan progradational deposits during the late stage.%通过对研究区沉积构造等相标志的研究,以层序地层学和沉积学原理为指导,结合室内岩石薄片、粒度分析,识别出冲积扇、辩状河和湖泊3种沉积相类型.并对官庄组的沉积相垂向演化和平面展布有了系统的认识.研究结果表明:新汶凹陷官庄组自下而上发育冲积扇-辩状河-湖泊和冲积扇两大沉积体系.沉积演化经历了早期凹陷掀斜下沉时的冲积扇、辩状河沉积,中期凹陷扩张阶段的湖泊相沉积,晚期凹陷收缩时的冲积扇进积沉积.